Synthesis and characterization of titanium and zirconium complexes with silicone-bridged phenoxycyclopentadienyl ligands

Abstract Dimethylsilyl(2,3,4,5-tetramethylcyclopentadienyl)(3- tert -butyl-5-methyl-2-phenoxy)titanium dichloride ( 1a ), a useful catalyst precursor for olefin copolymerization, was synthesized at high yield starting from allyl-protected phenolic ligand 3a ,which was first treated with 2 equiv. of n -BuLi to selectively give the dilithium salt of 3a along with 1-heptene, a coupling product of a protected allyl ether moiety and butyl anion. Addition of TiCl 4 to the resulting dilithium salt of 3a in toluene afforded 1a in 50% isolated yield. This methodology could be applied to the preparation of related titanium and zirconoium complexes 1b – 1d , 8 with silicone-bridged Cp-phenoxy ligands, whereas the reaction starting from methyl-protected precursor 2a did not produce the zirconium complex 8 . Copolymerization of ethylene and 1-hexene with the newly prepared complexes was also investigated.